Manipulating Fog with Lua/MML

[ktaur]

A while back, i remember someone made a map with fog that cycled through a number of different colors and other properties. Not for any lack of trying, i've been unable to find it again.

Setting fog properties like color and density in MML is very straightforward; what i'm trying to do, ultimately, is make changes to those properties dynamically, based on particular events; for example, player activates a switch or enters a specific polygon, and the fog thickens or changes color.

For instance, a map i'm working on features airlocks between indoor and outdoor (vacuum) environments. Dynamically turning on fog that quickly "thickens," turning an opaque white before fading to zero opacity again, thus appearing to dissipate—simulating oxygen decompression—would make the cycling of the airlock seem more realistic. Another part of the same map features a long lift ride into a deeper subterranean area, which could be made a lot creepier with some fog that gradually appears as the platform descends into darkness.

Admittedly, i'm no pro when it comes to Lua, but i'm sure i could figure out the finer points. Even after looking over the scripting guide, i can't seem to figure out how to how to invoke fog...

[The Man]

This lightly edited code from Where Monsters Are in Dreams causes fog to fade out when the player finishes the level. (I've cut out a few things you probably won't need.)

Code: Select all

Triggers = {}

function Triggers.init(saved_game)
	Game.proper_item_accounting = true
	if saved_game then
		a = Game.restore_saved()
		if not a then
			error("restoring data failed")
		end
	else
		Game._finished = 0
		Game._countdown = 210
		Level.fog.active = true
		Level.fog.present = true
		Level.fog.affects_landscapes = true
		Level.fog.depth = 16
		Level.fog.red = 0.25
		Level.fog.green = 0.1
		Level.fog.blue = 0.24
		Level.underwater_fog.active = true
		Level.underwater_fog.present = true
		Level.underwater_fog.affects_landscapes = true
		Level.underwater_fog.depth = 16
		Level.underwater_fog.red = 0.21
		Level.underwater_fog.green = 0
		Level.underwater_fog.blue = 0.07
	end	
end

function Triggers.idle()
	if Game._finished == 0 then
		if Level.calculate_completion_state() == "finished" then
			Game._finished = 1
			Game._countdown = 210
		end
	else
		if Game._countdown then
			if Game._countdown > 0 then
				Game._countdown = Game._countdown - 1
				Level.fog.depth = Level.fog.depth * 1.01125994634
				Level.underwater_fog.depth = Level.underwater_fog.depth * 1.00792758236
			else
				Level.fog.active = false
				Level.fog.present = false
				Level.fog.affects_landscapes = false
				Level.underwater_fog.depth = 42
				Level.underwater_fog.affects_landscapes = false
			end
		end
	end
end

Another function used in several Eternal 1.3 levels causes fog's brightness and depth to fade in and out, and to flicker during a rainstorm. You can see it in our split map folder - the first level that uses it is "A Friend in Need", which also uses platforms to activate a map behaviour (it retextures parts of the level and activates the precipitation script over those parts. I'd recommend not trying too hard to wrap your head around the precipitation stuff for now, though - it's just important that the script changes the assignments for precipitation objects on those polygons. Which isn't the best way to do it, but it was the easiest when I wrote it, and I've left it because I have too many other things to do). Between all of that, you should get ideas of how to do some of this stuff, though my code isn't the most efficient or well-constructed.

Hopefully some of this helps. I won't have time to provide a more detailed answer until late this month, but it'd probably be more helpful in the long run for you to figure how to script some of this stuff out yourself, anyway.

[ktaur]

Excellent, thank you! This is exactly what i was looking for. i was aware of precipitation effects and other stuff in Eternal, at least one of the maps in RyokoTK's Starlight ("Dissolution," i think?), and a few from Imperium. i'd tried to take a peek at the code, but Atque seems to have stopped working, so i can't split the maps.

The code you provided should be all i need to figure it out. Thanks again.

This lightly edited code from Where Monsters Are in Dreams causes fog to fade out when the player finishes the level. (I've cut out a few things you probably won't need.)

Code: Select all

Triggers = {}

function Triggers.init(saved_game)
	Game.proper_item_accounting = true
	if saved_game then
		a = Game.restore_saved()
		if not a then
			error("restoring data failed")
		end
	else
		Game._finished = 0
		Game._countdown = 210
		Level.fog.active = true
		Level.fog.present = true
		Level.fog.affects_landscapes = true
		Level.fog.depth = 16
		Level.fog.red = 0.25
		Level.fog.green = 0.1
		Level.fog.blue = 0.24
		Level.underwater_fog.active = true
		Level.underwater_fog.present = true
		Level.underwater_fog.affects_landscapes = true
		Level.underwater_fog.depth = 16
		Level.underwater_fog.red = 0.21
		Level.underwater_fog.green = 0
		Level.underwater_fog.blue = 0.07
	end	
end

function Triggers.idle()
	if Game._finished == 0 then
		if Level.calculate_completion_state() == "finished" then
			Game._finished = 1
			Game._countdown = 210
		end
	else
		if Game._countdown then
			if Game._countdown > 0 then
				Game._countdown = Game._countdown - 1
				Level.fog.depth = Level.fog.depth * 1.01125994634
				Level.underwater_fog.depth = Level.underwater_fog.depth * 1.00792758236
			else
				Level.fog.active = false
				Level.fog.present = false
				Level.fog.affects_landscapes = false
				Level.underwater_fog.depth = 42
				Level.underwater_fog.affects_landscapes = false
			end
		end
	end
end

Another function used in several Eternal 1.3 levels causes fog's brightness and depth to fade in and out, and to flicker during a rainstorm. You can see it in our split map folder - the first level that uses it is "A Friend in Need", which also uses platforms to activate a map behaviour (it retextures parts of the level and activates the precipitation script over those parts. I'd recommend not trying too hard to wrap your head around the precipitation stuff for now, though - it's just important that the script changes the assignments for precipitation objects on those polygons. Which isn't the best way to do it, but it was the easiest when I wrote it, and I've left it because I have too many other things to do). Between all of that, you should get ideas of how to do some of this stuff, though my code isn't the most efficient or well-constructed.

Hopefully some of this helps. I won't have time to provide a more detailed answer until late this month, but it'd probably be more helpful in the long run for you to figure how to script some of this stuff out yourself, anyway.

[The Man]

“Dissolution” doesn’t have precipitation, but it does vary the fog levels. “Iconic Something”, “Flank Speed”, “Phantom Power”, “Hyacinth House”, “Inaugural Trams”, and “End Times” are the Imperium maps that use precipitation; “Dead by Daybreak” and “End Times” also vary the fog. Also, for some reason “Inaugural Trams” has a secret terminal asking me, specifically, if I cheated to find it.

(At last count, I think sixteen Eternal maps use precipitation: “A Friend in Need”, “Unpfhorseen”, “Pissing on the Corporation”, “My Kingdom Pfhor a Horse”, “Burning Down the Corporation”, “The World Is Hollow”, “Eat S’pht and Die”, “Second to Last of the Mohicans”, “The Land in the Sky”, “The Incredible Hulk”, “Babylon X”, “Floating in the Void”, “The Dead Live in the Catacombs”, “We Met Once in the Garden”, “Where Giants Have Fallen”, and “The Near Side of Everywhere”.)

I’d recommend reporting the Atque bug on GitHub, or just making a separate thread for it or notifying treellama on Discord. Hopefully it’s fixable.

Anyway, glad that helped.